The present invention generally relates to side impact air bag systems and more particularly to an apparatus that may be integrated within the covering material of an automotive seat to controllably open a portion thereof upon deployment of an air bag.
Currently side impact air bag systems are either mounted within the vehicle door or integrated within the front driver or passenger automotive seat. FIG. 1 is illustrative of a typical side impact system mounted to a vehicle seat 22. The seat comprises a seating portion 24 and seat back 26 includes a front surface 28, a side 30 and a rear surface 32 and one or more structural components 34 generally shown as a reinforcing bar used to support seat back 26. A fabric, vinyl or leather seat cover 27 is fitted about a formed pad or foam cushion 35. The seat cover 27 includes a front 28', side 30' and rear 32' fabric cover portions or panels fitted over the foam 35. An air bag module generally shown as 40 is fitted within a recess within the padding or foam 35 in the side 30 of the seat back 26. The air bag module 40 typically comprises an inflator, housing, air bag and hinged deployment door or trim cover 42. When the air bag opens it presses on the hinged door 42, hinged along its rear side, opening same permitting the air bag to inflate between the vehicle side and the adjacent side of the occupant to be protected. These doors are typically fitted about the outside of the fabric cover 27 and may be supported by the structural member 34. The externally mounted door or trim cover requires an opening in the seat cover side panel 30'. This opening often adversely impacts the fit and finish of the side panel 28' since this opening makes it difficult to achieve the desired tension (smoothness) in the seat cover (trim) fabric. This type of construction is inefficient and raises the cost of the overall seat and air bag system and also requires the precise alignment between the trajectory of the inflating air bag and the position of the door 42 and location of the opening in the side panel which may be difficult to achieve. Another major problem with a rigidly mounted deployment door arises from the fact that the outline of the finished, sewn side panel 30' and its orientation relative to the padding is not the same for all seats within a car line. This outline can vary up to 20 mm since the locations of the various seams 44a,b,c of the cover 27 are not controlled to a high degree. Consequently, the location of the opening in the side panel will vary from car to car. The result of this is that the air bag module manufacturer probably would either have to make some type of compensating feature to adjust for the different seat trim outlines or make a number of modules that would be matched to the seat trim outline at the time of assembly to provide an acceptable fit and finish. This of course further increases the price of the system. Further, since the door is exposed it may be damaged by the occupant and may fatigue after a number of occupant ingress/egress cycles, or physically deteriorate as it is exposed to the sun, dirt, water, etc. This type of cover, which is a rigid body may also create an occupant discomfort factor as it may reduce the overall compliance (softness) of the cushioned seat.
As is known in the art, the various parts of the automotive seat are sewn together along various seams such as 44a,b,c. One suggestion is to eliminate the use of a separate, exterior door and rely upon the inflating air bag to rip the forward seam, such as 44a, to provide an egress opening through which the side impact air bag expands as it continues to inflate. While this proposal has merit, it provides a contradiction that can be seen below. To ensure that the air bag is consistently deployed, the front seam 44a needs to be sufficiently weak to enable the air bag to rip it open in a predictable manner. Alternatively, the size of the inflator could be increased to compensate for the increased seam strength insuring that the seam is properly ripped. This in turn requires a stronger mounting bracket, housing, bag, etc. However, utilizing a weak seam may, over the 10 to 15 year useful life of the vehicle, cause a degradation in the strength of the seat cover 27. If the seam is reinforced to insure it does not come apart due to normal wear, the air bag will not be able to rip the seam open and must then rip or tear through the side covering panel material 30'. As there are lot-to-lot differences between seemingly identical woven, knitted, vinyl or laminated fabrics or natural covering material such as leather and certain cloths it becomes difficult to predict just where the side panel 30' will rip. Consequently, the ability of the air bag to cleanly and consistently rip through the covering material will vary from lot to lot. As can be appreciated, the consistency of air bag deployment will be affected by any variability in the construction of the seams and the consistency in the threads used.
We have found that one major contributor to the variability in the performance of side impact air bag systems is the elongation, or variation in elongation, of the material used as the cover. The present invention has demonstrated the ability to overcome this variability to achieve consistent and repeatable performance through a -40.degree. C. to +85.degree. C. temperature range.
It is an object of the present invention to provide a side impact deployment mechanism that solves the deficiencies in the prior art. A further object of the present invention is to provide a side impact mechanism that is invisible and one that does not detract from the aesthetics and comfort of the automotive seat. A further object of the present invention is to provide a reaction surface or reinforcement panel mechanism that protects an adjacent air bag from occupant tampering and subsequent damage.
Accordingly the present invention comprises: a material cover for a vehicle seat, the seat having a seat back cushion having a front surface, a rear surface and a side surface covered by a material cover. The vehicle seat may be any seat within the vehicle. The material cover includes a front panel, rear panel and side panel covering the front, rear and side of the seat back. In one of its preferred embodiments the invention further includes first means secured to an inside surface of the side panel of the seat cover for effectively decreasing the elongation of the side panel, for localizing stress in the side panel and encouraging the side panel to tear along a determinable tear line generally proximate a side of the first means as the first means is forced outwardly by the action of an inflating air bag. In one embodiment of the invention the first means includes a thin, flexible reinforcement panel sewn to the inside of the side panel and in another embodiment the reinforcement panel is formed from a layered construction of a plurality of thin, lightweight pieces of fabric. In another embodiment of the invention the side panel of the cover itself is made of a low elongation material.
Many other objects and purposes of the invention will be clear from the following detailed description of the drawings.